GetStockSections has been made interface only, like the GetCustomSections function that returns a list of ISectionModule. Also added missing null check (should never be encountered but no harm in having robust code).
GetStockSections has been made interface only, like the GetCustomSections function that returns a list of ISectionModule. Also added missing null check (should never be encountered but no harm in having robust code).

 Binary files a/Assets/Plugins/KerbalEngineer.Unity.dll and b/Assets/Plugins/KerbalEngineer.Unity.dll differ
--- a/KerbalEngineer/Flight/FlightAppLauncher.cs
+++ b/KerbalEngineer/Flight/FlightAppLauncher.cs
@@ -62,7 +62,7 @@
         /// <summary>
         ///     Gets a list of stock sections.
         /// </summary>
-        public IList<ISectionModule> GetStockSections()
+        IList<ISectionModule> IFlightAppLauncher.GetStockSections()
         {
             return new List<ISectionModule>(SectionLibrary.StockSections.ToArray());
         }
@@ -178,7 +178,7 @@
             {
                 m_FlightMenu.Close();
             }
-            else
+            else if (m_MenuObject != null)
             {
                 Destroy(m_MenuObject);
             }

 Binary files a/Output/KerbalEngineer/KerbalEngineer.Unity.dll and b/Output/KerbalEngineer/KerbalEngineer.Unity.dll differ
 Binary files a/Output/KerbalEngineer/KerbalEngineer.dll and b/Output/KerbalEngineer/KerbalEngineer.dll differ